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Published January 1995 | public
Journal Article

Preparation of H_2 Permselective Silica Membranes by Alternating Reactant Vapor Deposition

Abstract

Thin SiO_2 layers were deposited on the surface of porous Vycor glass by alternating vapor phase reaction with SiCl_4 and H_2O. The membranes prepared by this technique had a H_2 permeance of 0.3-0.4 cm^3(STP)/(min•cm^2•atm) and a H_2:N_2 selectivity of 500-1000 at 600 °C. The SiCl_4 dosage at each silylation cycle, the concentration of initial surface OH groups, and the reaction temperature significantly influence the deposit layer thickness. After two weeks of heating at 550 °C under 3 atm of water vapor, the membrane H_2 permeance decreased by about 20%, and the selectivity increased to more than 2000. The membrane properties after this hydrothermal treatment are superior to those of membranes prepared earlier by one-sided (steady flow) deposition. A simple model incorporating diffusion and surface reaction was used to study the effect of various parameters on the formation of the deposit layer.

Additional Information

© 1995 American Chemical Society. Received for review January 25, 1994. Revised manuscript received July 26, 1994. Accepted September 23, 1994. The authors appreciate the funding of this work by the Department of Energy under the University Coal Research Program, Grant DE-FG22-92PC92525. Corning Inc. graciously donated the porous Vycor tubes.

Additional details

Created:
August 20, 2023
Modified:
October 24, 2023